Re: [boost] [Review] XInt Review

Subject: Re: [boost] [Review] XInt Review
From: Simonson, Lucanus J (lucanus.j.simonson_at_[hidden])
Date: 2011-03-09 13:14:21

Steven Watanabe wrote:
> AMDG
> 
> On 03/04/2011 01:22 PM, Joel Falcou wrote:
>> On 04/03/11 22:17, Marsh Ray wrote:
>>> Is it a requirement for Boost that every new library be
>>> state-of-the-art in its use of compile time polymorphism?
>> 
>> Maybe, maybe not. Now, I remind you that Phoenix have been delayed
>> as being accepted into boost the first time, consensus being it has
>> to use proto to be accepted.
> 
> Phoenix is a very different case.
> 
> a) We already had Lambda which provides the same basic
>     functionality.
> b) The choice for phoenix was between using expression
>      templates with proto or without proto.  The choice here
>      is between using expression templates with proto and
>      not using expression templates at all.

This is a serious question that I'm posing with all humility.  What benefit does proto provide in this case?  What do we "get" for using it and what does it "cost".  Can you sketch a comparison between an expression template operator+ on some concrete big int type both with and without use of Proto and walk us through how the use of proto is helpful and worthwhile?  I can already reason that compile time with Proto will be higher than without, though I would be convinced by benchmarks to the contrary.  We don't need concept checking in this case, so what does proto buy us?

Regards,
Luke